Inflatable packer or element



April 16, 1963 E. o. SODICH 3,085,627

INFLATABLE PACKER OR ELEMENT Filed Aug. 15, 1958 3 Sheets-Sheet 1 i I Ii I z A4 45, s M

ATTOR/VE VJ April 16, 1963 E. o. SODICH 3,

INFLATABLE PACKEZR OR ELEMENT Filed Aug. 15, 1958 5 Sheets-Sheet 3 J 0 ac fi INVENTOR Ernesf 0.

BY y M 3,085,627 INFLATABLE PACKER R ELEMENT Ernest 0. Sodich, Houston,Tex, assignor to Lynes, Inc, a corporation of Texas Filed Aug. 15, N58,Ser. No. 755,177 7 Qlairns. (Cl. 166-120) The present invention relatesto an inflatable element.

When packers or inflatable elements are lowered into well bores in orderto seal off a portion of the well bore, there is sometimes a tendencyfor the packer to move or slide along the well bore wall as a result offluid pressure acting thereon. Such conditions arise where the well boreis cased, so that-the bore wall is relatively uniform and has no surfaceirregularities which might aid in anchoring the hydraulic packer inposition after it has been inflated. Also, many holes drilled into theearths formation are smooth and slick even without casing so that theproblem is prevalent whether the hole is cased or not.

Noninflatable types of packers are generally provided with suitablehold-down means such as slips or the like, which are adapted tofrictionally engage the wall of the well pipe, whereupon the packer canthereafter be expanded to sealing position within the well pipe. It isundesirable to provide a hold-down tool for maintaining the packer inposition in the .well pipe whether the packer be a squeeze type ofpacker which is adapted to be expanded by exerting a force or squeeze ona large mass of rubber as distinguished from inflatable packers, whichare adapted to be expanded by fluid pressure applied internally thereof.

It may also be desirable to seal off a flow line while repairs are madetherein, or to seal off a tubular member to test for leaks, and invarious other situations it is desirable at times to seal oil. in anannulus.

An object of the present invention is to provide an inflatable packerwhich will remain seated in either a cased or open hole, even under highdifferential pressures.

Another object of the present invention is to provide an inflatableelement construction which is provided with a friction area on the bodythereof so as to maintain the element seated in position in an annularmember;

Still a further object of the present invention is to provide aninflatable element which is adapted to be expanded in a well bore toseal with the well bore wall, which element includes force concentratingmeans thereon to concentrate and thereby magnify the sealing or seatingpressure of the packer against the -well bore wall so as to anchor thepacker firmly in the well bore.

Still a further object of the present invention is to provide a packerincluding spaced annular heads, a packer body extending therebetween,reinforcing in said body and secured to each of said heads, andparticles positioned on the exterior of said body which are adapted tofrictionally engage the -well bore wall and concentrate the inflatingpressure within the packer on said particles to aid in seating thepacker within the well bore.

Still a further object of the present invention is to provide aninflatable element for a well bore including means to concentrate andmagnify the inflating pressure of the element so as to aid in seatingand maintaining the packer seated in position in the well bore.

Yet a further object of the present invention is to provide aninflatable packer construction which is constructed and arranged so thatit will remain seated within a well pipe, or tubular object.

A further object of the present invention is to provide spaced frictionareas on the external periphery of a fluid inflatable packer body, sothat after the packer has been inflated and seated within well pipe, itwill maintain its original seated position.

Still a further object is to provide an inflatable packer body havingrecessed friction areas thereon which engage the wall in a well borewhen the packer is inflated so as to properly seat, and maintain thepacker seated within the well even though substantial differentialpressure within the well is effective to act on the packer.

Other and further objects of the present invention will become morereadily apparent from a consideration of the following description anddrawings, wherein:

FIG. 1 is a view illustrating a form of the inflatable packer of thepresent invention in deflated position and being lowered into well pipe,with a well pipe shown in section;

FIG. 2 is a view somewhat similar to FIG. 1, but showing the inflatablepacker expanded or inflated and in seated position within the well;

FIG. 3 is a sectional view on .the line 3-3 of FIG. 2 showing in moredetail the construction of a form of the friction areas or forceconcentrating means on the packer body and its relationship to theinternal periphery of the well pipe when the packer is expanded andseated within the well pipe;

FIG. 3A is an enlarged view illustrating one particle of the abrasivematerial which is embedded in the packer body;

FIG. 4 is a side view, illustrating an alternate modification of thefriction means or force concentrating means for use on the packer body;

FIG. 5 is a sectional view on the line 5-5 of FIG. 4, illustrating inmore detail, the structural arrangement of the friction, or forceconcentrating means of the FIG. 4 modification and its arrangement onthe packer body;

FIG. 6 is a side view of still another modification of the friction orforce magnifying means for use on the packer body;

FIG. 7 is a sectional view on theline 7-7 of FIG. 6 to show in moredetail, the structural arrangement of the friction means of the FIG. 6modification;

FIG. 8 is an elevational view, partly in section, wherein an alternatearrangement of the force concentrating and magnifying means of theinvention is illustrated, and also illustrating in more detail thepreferred embodiment of the internal structural arrangement of thepacker or element;

FIG. 9 is a sectional view on the line 9-9 of FIG. 8;

FIG. 10 is a sectional view on the same line as FIG. 9 but showing thearrangement or relationhip of the element components when the element isinflated; and

FIG. 11 is an enlarged schematic representation to illustr-ate thefunction of the force concentrating means of the present invention.

The present invention will be described in detail as it may be used forpositioning in a well pipe in a well bore. However, it should beunderstood that such description is purely for purposes of explanation,and that the present invention may be as easily used in any annularmember wherein it is desired to seal off the member, either to test it,for repairs, or for other reasons.

Attention is directed to FIG. 1 of the drawings wherein a Well pipe isillustrated at 2, which well pipe is positioned within the well bore 3formed in the earth 4. The packer or element forming the presentinvention is illustrated generally by the numeral 5 and is adapted to belowered within the Well pipe 2 by any suitable means such as byconnecting a male adapter 6 threadedly to the packer as shown in P16. 4,and then connecting the well string 6 to the fitting 6, as shown inFIG. 1. The well string ex.- tends upwardly to the earth's surface and,if desired, the well string 6 may extend below the packer as illustratedat 7 in FIG. 1, depending upon what the packer or packers are toaccomplish within the well bore 3.

After the packer has reached the elevation within the well pipe 2 atwhich it is desired to expand the packer in sealing engagement with thewell pipe, the packer may be inflated by discharging fluid from the wellstring 6 through a port therein (not shown) internally into the packer5. Suitable mechanism, shown in the prior art, may be connected to thewell string and packer in order that it may be inflated, as desired. Asthe packer inflates, it will expand radially until the packer engagesthe internal periphery of the pipe 2 as illustrated at 8 so as to sealoff a portion of the well bore 3.

It will be noted that the present invention is described with regard toonly one packer; however, a plurality of packers can be provided inorder to treat or test the well, as desired, in which event all of thepackers may be provided, if necessary, with friction areas as describedhere inafter.

The details of the packer arrangement on the well pipe 6 and theoperating mechanism for inflating the packers are not described herein,since such construction and arrangement on the well pipe are Well knownin the art, for example, as shown in Patent No. 2,824,612, issued toJohn Lynes on February 25, 1958. The representation in the drawings ismerely illustrative and the above patent, as well as others may bereferred to for details of connection and arrangement of the packers onthe well string 6. The prior art also illustrates means whereby thepacker may be inflated and, therefore, the details of inflating anddeflating the packers 5 are not described herein.

The packer designated generally by the numeral 5 in FIG. 1 is shown inmore detail in the modification illustrated in FIG. 8. The packer orinflatable element 5 includes annular heads 9 and arranged in spacedrelation to each other to form the ends of the packer and the body 11extending therebetween. The packer body represented generally at 11which extends between the heads 9 and 10 is secured thereto by anysuitable means as disclosed in Patent No. 2,611,437, issued to JohnLynes on September 23, 1952.

The body 11 includes resilient material 11' and suitable reinforcing asshown at 11" therein to withstand the internal and external pressure-sapplied thereto during inflating and the external and internal pressuresapplied thereto during functioning of the packer in the well bore. Thereinforcing 11" is shown as being formed by a plurality of strips 11"which extend longitudinally of the body 11 of the packer 5 and aresecured to each head 9 and 10, as will be described in more detailhereinafter. The longitudinally extending strips 11" of reinforcing 11are arranged within the packer body 11 so that adjacent strips overlieeach other longitudinally between the heads 9 and 16.

FIG. 9 shows the packer 5 in deflated position and FIG. 10 representsthe packer or inflatable element 5 inflated. As shown in FIG. 10, thelongitudinally extending strips 11" of the reinforcing 11 remain inoverlapped relation although the degree of the overlapping is not asgreat as it is when the packer is deflated as shown in FIG. 9. Thus, thereinforcing which is formed of material of relatively great tensilestrength serves to reinforce the body 11 of resilient material and aidsin retaining the inflating fluid even when the packer is inflated.

Each annular head may be provided with a recess as illustrated at 9' onthe outer periphery and at the inner end so that the body 11 may fitclosely about each of the heads. Serrations or a knurled surface 9" isprovided on the inside of each head which engages the ends 11a of thestrips 11" to aid in securing the reinforcing 11" to each of the heads 9and 10. A member 11b may be provided for fitting within each of theheads 9 and 10 to engage the ends 11a of the reinforcing strips 11 inorder to anchor the ends 1111 of the longitudinally extendingreinforcing strips 11" in position in each of the heads 9 and 10. Itwill be noted that serrations 11c are provided on the lower end of themember 1112 which are adapted to engage the ends 11a of the reinforcingstrips 11' and as the member 11b is driven by pressure into a tight fitwith each of the heads 9 and 10, the serrations 11c thereon will engageagainst the ends 11a of the strips 11" to firmly secure the reinforcing11" in position in each of the heads 9 and 10. It will be noted that aportion of the resilient material 11' of the packer body 11 extendsupwardly within the member 11!) and this portion of the packer body maybe retained in position therein by suitable means such as the brass orbronze ring 11:] which may be expanded by pressure to seat within themember 1112 as shown in FIG. 8 of the drawings.

The packer body 11, including the heads, the reinforcing 11", and thearrangement of the resilient material 11 of the packer body serve toretain the inflating fluid within the packer when the packer isexpanded. The reinforcing 11" and the heads 9 and 10 also provideadditional strength to the packer 5 to aid in withstanding the highpressures necessary to a proper functioning of the packer when it isexpanded to seat or seal within the well bore 3.

In the FIG. 8 modification, it will be noted that a friction area orforce concentrating means represented generally by the numeral 15 isprovided on the packer or inflatable element 5, which extends throughoutthe length of the resilient material 11 between the heads 9 and 10 ofthe body 11 of the packer.

The FIGS. 1 and 2 modification show packer body 11 as being providedwith annular recesses 13 and 14 which are spaced relative to each otheron the periphery of the resilient material 11' and adjacent the heads 9and It The recesses 13 and 14 are formed in the resilient material 11 inany suitable fashion, as, for example, the recesses 13 and 14 may beformed by suitable cutting means which cuts the recesses 13 and 14 inthe resilient material 11' after the packer body 11 has been formed.

It will be noted that each recess 13 and 14 of the FIGS. 1 and 2modifications, as well as the entire body 11 of the FIG. 8 modification,is provided with a coating of abrasive particles 17 or material to formthe friction areas or force concentrating means 15 on the packer orinflatable element 5. The particles 17 are bonded on the body 11 of theFIG. 8 modification and are embedded within the recesses 13 and 14 ofthe body 11 in the FIGS. 1 and 2 form. The abrasive particles 17 are ofa hard substance such as metal or the like, and each particle has aplurality of edges and surfaces which are irregular and protrudeoutwardly relative to the body 11 of the packer 5 to aid in frictionallygripping the inner periphery 8 of the well bore when the packer '5 isexpanded or inflated as shown in FIG. 2 of the drawings. Moreparticularly, the abrasive particles 17 may be formed of cracked metalshot, carborundum or aluminum oxide grit, or may be in the form of thecircular buttons at shown in FIG. 4, or the jaw segments as shown inFIG. 6. Additionally, other forms of frictional areas or forceconcentrating means may be provided on the packer without departing fromthe scope of the invention.

It has been further discovered that the arbrasive coating of particles17 may be applied to the annular recesses or grooves 13 and 14 bywrapping the recesses 13 and 14 with uncured resilient material orsynthetic rubber and then providing a surface on the uncured materialwith a suitable cement which is sticky in nature. The particles 17 maythen be placed manually on the sticky surface within the grooves 13 and14, and the packer or element 5 then subjected to suitable heat so as tocure the material, whereupon the hard particles become firmly embeddedwithin and bonded to the cured rubber in the recesses 13 and 14 and arethereby integrally formed with the packer body 11.

If the resilient material is synthetic or natural rubber, the portionwithin the recesses 13 and 14 of the FIGS. 1 and 2 modification may besoftened with methyl ethyl ketone or ethylene dichloride, either ofwhich softens syn thetic or natural rubber and makes it sticky,whereupon the particles 17 may be placed in each of the recesses. Ofcourse, in the FIG. 8 modification, the entire body '11, between theheads 9 and 10 would be correspondingly treated so as to retain theparticles 17 thereon, while the resilient material is cured.

In order to aid in bonding the particles 17 on the packer body 11,either in the FIGS. 1 and 2 modification, or in the FIG. 8 modification,they should be coated with a suitable material prior to placing them onthe packer body 11 in order to facilitate bonding of the particles tothe resilient body 11.

It has been further discovered that the metallic or hard particles 17forming the abrasive friction surface or force concentrating means needonly be one layer thick, in order to perform the desirable function offirmly gripping and concentrating a force against the inner periphery 8of the well pipe 2.

In FIG. 2 the packer construction 5 is illustrated as having beeninflated, and it will be noted that the packer body '11 has beenexpanded and the grooveslfi and 14 therein also expand radially with theresilient body 11' to engage the inner periphery 8 of the well bore.Since the grooves 13 and 14, and the abrasive particles 17 therein, arearranged adjacent each end of the packer, and in spaced relation, thepacker is thus firmly held in position in the well pipe 2, so that anytendency from pressure acting above or below the packer which tends tomove the packer in the well pipe is resisted. Thus, the packer is firmlyseated within the well pipe 2, and treating or testing operations, asdesired, can be carried out without running the risk of having theexpanded packer slip or move along the well pipe.

FIG. 3 illustrates the inflated position of the packet, and it will benoted that the particles 17 have a plurality of sharp edges andirregular surfaces thereon and tend to dig into the inner periphery 8 ofthe well pipe 2 to aid in gripping the well pipe and transmitting aconcentrated force from the packer to the pipe or Well bore.

FIG. 3A represents in enlarged form one of the particles 17 embedded inthe recesses 13 and 14 on the packer body 11. Of course, each particlewill be of different configuration and shape, but it will be noted thatas shown in FEG. 3A, the particle 17 includes many edges '18, '19, 2t 21and 22 which are, of course, joined by their respective surfaces, whichare irregular as represented by the numeral 23. The lack of uniformityof the particles 17, as well as their irregular surfaces and edges aidsin providing a plurality of smaller individual surfaces which define thefriction surface 15 that positively grips the pipe 2 or the well borewall to prevent movement of the packer 5 therealong.

The particles 17 also form a means so that the force of the inflatingpressure of the well packer may be concentrated and magnified to aid inretaining the packer in position in the well, and to prevent slippingthereof, even though the pressure differentials within the well maybecome great. For example, attention is directed again to FIGS. 3 and3A, and as previously mentioned, the particles 17 are provided with aplurality of edges joined by irregular surfaces. The particles 17 areembedded and bonded within the packer body 11 and protrude therefrom sothat as the packer body llexpands to engage the wall of the well bore,the inflating pressure within the packer is transmitted through theresilient body 11' of the inflatable element 5 to the surroundingformation against which the element 5 is seated. Since the particles '17protrude relative to the resilient body 11' of the packer 5, the exposedsurfaces of the particles 17 bear against the adjacent well wall. istingwithin the packer, instead of being uniformly distributed along whatwould normally be a smooth outer periphery of the resilient body 11' ofthe packer 5, is transmitted to the protruding edges of each of theparticles 17. These edges, being much smaller in total area thanTherefore, the fluid pressure exwithin the resilient packer body 11.

the edge of the button 25'.

the total area of the resilient body 11 therefore serve to concentratethe force from the inflatable element or packer 5 and tend to magnifythe pressure along each edge so that a greater force is exerted by thepacker 5 than would otherwise be the case to aid in seating it properlywithin the well bore. As previously mentioned, the force concentratingmeans 15 shown in FIGS. 1, 2 and 8 as being in the form of the particles17 is harder than the pipe in a well bore, and is harder than the wallof a well bore so that the force applied from the inflating element tothe sharp edges of the particles tend to dig into the pipe or into thewall of the well bore because of the force magnified thereon. Theresilient material 11' in the body '11 of the inflatable element orpacker 5 is such that it will elongate, but its hardness preferably issuch that the resilient material will not always contact the wall of thewell or pipe when it is expanded. In other words, the major portion ofthe force transmitted to the wall of the well bore or to the pipe inwhich the packer is positioned, will be that force concentrated throughthe force concentrating means on the edges of each of the protrudingparticles 17, while only a portion of the force is transmitted by theresilient'material directly to the surrounding wall of the annulus inwhich the element is positioned. In FIG. 4 the packer construction isagain represented generally by the numeral 5, and it will be noted thatthe packer body 11 is provided with a plurality of members designatedgenerally by the numeral 25 within the resilient material 11' to formfriction are-as or force concenrating means 15 adjacent each end of thepacker. The members 25 are shown as being in the form of circularbuttons 25 which are arranged in rows as shown at 26, which rows may bein staggered circumferential relationship to each other, if desired, asshown at 27. The buttons 25' may be embedded in the resilient material11 in any suitable manner, such as by integrally forming the memberstherein at the'time that the packer body 11 is formed with uncuredrubber and thereafter cured by heating.

In FIG. 5, the details of the buttons 25 are shown as well as theircircumferential relationship to each other It Will be noted thatthebuttons 25 are providedwith the surface 30 thereon which is taperedinwardly and annularly as shown at 31 to form the edge 32 where thetapered surface 31 meets Therefore, when the packer body 11 is inflatedto expand it, the edge 32 of each button is exposed to engage with theperiphery 8 of the well, and tends to dig into the periphery of the wellto inhibit movement of the packer therealong. It will be further notedthat the buttons 25' are grouped adjacent each end of the packer body 11to form friction areas 15 adjacent each end of the packer in a manner asdescribed with regard to the FIGS. 1 and 2 modification.

In FIG. 6, the members 25 are represented as being in the form of jawsegments 33, which segments may be arranged in rows 34 on the'packerbody 11, and in staggered circumferential relationship as shown at 35,if desired. The segments 33 are provided with serrations or otherirregular surface areas thereon as shown at 36 so that when the packerbody 11 is expanded, the jaw segments engage with the inner periphery 8of the well. Jaw segments 33-are shown as being grouped adjacent eachendof the packer in the FIG. 6 construction in a manner similar to thebuttons 25' of the FIG. 4 modification, to form friction areas or forceconcentrating means 15 in the packer body 11.

It will be noted with regard to the FIGS. 4 and 6; modification, thatthe force concentrating the force magnification means 15 is illustratedas being in the form of the spectively, For example, in the form of theforce magniflcation means 15 illustrated in FIG. 5, the edges 32 of thebuttons 25' will be exposed as the packer is inflated so that theinflating force within the packer is transmitted through the body 11 tothe edges 32 of each of the elements 25'. In the FIG. 6 modification,the force transmitted from the packer is concentrated and magnified bymeans of the serrations, or irregular surface areas, on the jaw segments33.

From the foregoing it can be appreciated that other forms of forcemagnification and concentration means could be provided other than thatillustrated in the present drawings and description without departingfrom the scope of the present invention.

It will be further noted that in FIGS. 1-6 inclusive, there isillustrated a form of the invention wherein the friction areas or forcemagnification means is provided at spaced locations adjacent the ends ofthe packer or inflatable element 5, whereas in the FIG. 8 modification,it will be noted that the means 15 extends substantially throughout thelength of the resilient material 11' of the body 11 of the inflatableelement 5. Either form will work quite satisfactorily; however, by usingtwo friction areas as illustrated in the preferred embodiment shown inFIGS. 1-6 inclusive, the maximum resistance against sliding or slippingof the packer within the well bore in either direction is provided witha maximum sealing effect between the spaced areas.

In FIG. 11, an enlarged representation of the force magnification means15 is shown as being in the form of the particles 17. A portion of thepacker body 11 is shown and it will be noted that the resilient material11 of the packer body does not contact the wall of the adjacent wellbore in which the packer is expanded. Therefore, the inflating pressurerepresented by the arrow 60 is transmitted to the protruding edges 61 ofthe particles 17 which contact the well bore wall. Thus, the inflatingpressure is concentrated on the contacting edges 61 instead of along theexterior 62 of the packer body 11. This magnifies the force, since thepressure must be distributed over the smaller areas of the contactingedges 61 so that the resistance to slipping of the packer is therebygreatly multiplied.

The function and operation of the present invention in any othersituation is similar to that previously described with regard to theexample in the well bore. If the device is to be used in an annulus of awell bore to seal against the well bore wall, the force magnificationmeans will act to concentrate the force against the well bore wall in amanner as previously described with regard to concentrating the forceagainst the periphery of the well pipe. Also, where the device is to beused in any annulus, or in a tubular object, for purposes of testing, orfor any other use, the force magnification means functions in the manneras described with regard to the force magnification means in the samemanner as previously described with regard to the use of the inventionin well pipe in a well bore.

Broadly the invention relates to an inflatable packer or element, andmore particularly to an inflatable packer which is provided with afriction surface area or force magnification means for aiding ingripping the well bore wall when the packer element is inflated andseated therein, or for gripping the surrounding wall in any annulus inwhich it is positioned.

What is claimed is:

1. An inflatable packer construction including spaced annular heads, anannular body of resilient material extending between and secured to eachof said heads, a pair of spaced recesses on the external periphery ofsaid body, and abrasive material embedded within said recesses to formfriction areas on the packer when inflated to aid in anchoring thepacker in inflated position, said abrasive material forming the frictionarea being in the form of a coating of particles on said body recesshaving protruding edges and surfaces.

2. An inflatable element adapted to be inflated and seated in a tubularobject including a support head adjacent each end of the element, anannular body of resilient material extending between and secured to eachof said heads, said body including a reinforcing sheath extendingbetween and secured by each of said heads, at least one recess on theexternal periphery of said body, and force concentrating means embeddedin said recess on said annular body of resilient material to aid inanchoring said body in the well bore.

3. An inflatable element adapted to be inflated and seated in an annulusincluding a support head adjacent each end of the element, an annularbody of resilient material extending between and secured to each of saidheads, said body including a reinforcing sheath extending between andsecured to each of said heads, and force concentrating means embedded insaid annular body of resilient material to aid in anchoring said body inthe well bore.

4. An inflatable element adapted to be inflated and seated in an annulusincluding a support head adjacent each end of the element, an annularbody of resilient material extending between said heads, said bodyincluding a reinforcing sheath extending between and secured to each ofsaid heads, and means forming a friction area embedded in said annularbody of resilient material to aid in anchoring said body in the Wellbore.

5. An inflatable element adapted to be inflated and seated in an annulusincluding a support head adjacent each end of the element, an annularbody of resilient material extending between said heads, said bodyincluding a reinforcing sheath extending between and secured to each ofsaid heads, and means forming a friction area on said annular body ofresilient material to aid in anchoring said body in the well bore, saidlast named means including particles of abrasive material which tend todig into the well bore wall when said element is expanded to anchor it.

6. An inflatable element adapted to be inflated and seated in an annulusincluding a support head adjacent each end of the element, an annularbody of resilient material extending between and secured to each of saidheads, said body including a reinforcing sheath extending between andsecured to each of said heads, means on said annular body of resilientmaterial to aid in anchoring said body in the well bore, said last namedmeans including particle means which concentrate and thereby magnify thepressure of the inflating body element against the well bore wall toanchor said body in the well bore.

7. In an inflatable element which is adapted to be expanded in a tubularbore to seal with the tubular bore wall, said element including anannular body of resilient material, friction means on said body to aidin anchoring said element in the tubular bore, said friction meansincluding particles embedded in said element, said particles havingirregular edges and surfaces which protrude outwardly relative to saidelement to concentrate and thereby magnify pressure of the inflatingelement against the tubular bore Wall to anchor the element in thetubular bore.

References Cited in the file of this patent UNITED STATES PATENTS2,019,418 Lang Oct. 29, 1935 2,084,784 Stahl June 22, 1937 2,171,438Tarbox Aug. 29, 1939 2,194,331 Strom Mar. 19, 1940 2,370,832 Baker Mar.6, 1945 2,656,891 Toelke Oct. 27, 1953 2,778,432 Allen Ian. 22, 19572,800,186 Tausch July 23, 1957 2,835,329 True May 20, 1958 2,970,649Brown Feb. 7, 1961

7. IN AN INFLATABLE ELEMENT WHICH IS ADAPTED TO BE EXPANDED IN A TUBULARBORE TO SEAL WITH THE TUBULAR BORE WALL, SAID ELEMENT INCLUDING ANANNULAR BODY OF RESILIENT MATERIAL, FRICTION MEANS ON SAID BODY TO AIDIN ANCHORING SAID ELEMENT IN THE TUBULAR BORE, SAID FRICTION MEANSINCLUDING PARTICLES EMBEDDED IN SAID ELEMENT, SAID PARTICLES HAVINGIRREGULAR EDGES AND SURFACES WHICH PROTRUDE OUTWARDLY RELATIVE TO SAIDELEMENT TO CONCENTRATE AND THEREBY MAGNIFY PRESSURE OF THE INFLATINGELEMENT AGAINST THE TUBULAR BORE WALL TO ANCHOR THE ELEMENT IN THETUBULAR BORE.